The objective of this study is 1) to determine what happens to microorganisms in carious dentin sealed from the oral cavity and 2) to determine whether dental caries progresses when occlusal pits and fissures are sealed with an adhesive resin polymerized by ultraviolet light. Carious pits and fissures of primary and permanent teeth, exhibiting clinical and radiographic signs of caries will be sealed and the progress of caries or lack, thereof, will be evaluated clinically and radiographically over time intervals of up to two or more years. At corresponding time intervals, the number and kinds of viable bacteria will be determined in the sealed lesions. Changes in the dentin, if they occur, will be determined histologically and microradiographically.